1. The Field of the Invention
The present invention relates to the fields of agriculture and horticulture. More particularly, the present invention relates to improved apparatus and methods for depositing hydrophilic polymers into existing sods.
2. The Prior State of the Art
It is well known that water is essential for plant growth and productivity. The amount of water that is required to sustain a plant, however, will vary depending on the climate, the type of plant, and the water holding capacity of the soil. Although rainfall and percolating ground water can satisfy some water requirements, irrigation is typically required as a supplement for providing an adequate and regular supply of water, for growing healthy and productive plants, particularly in arid climates.
Grass sod, which is commonly grown and groomed as an aesthetic covering for yards, parks, sports fields, golf courses, and other landscapes, is one example of a plant that typically requires supplemental irrigation for sustenance. To maintain the health and aesthetic appearance of the grass, it is essential that an adequate and regular supply of water be provided, approximately 0.5 inches per week, otherwise the grass will wilt and brown, and thereby frustrate the aesthetic and functional purposes for which the grass is grown.
One of the most popular irrigation methods is sprinkler irrigation. Sprinkler irrigation is popular because it is convenient and controllable and can therefore provide the regular supply of water that is required for growing healthy grass sod. One problem with sprinkler irrigation, however, is that it is expensive, even after discounting the initial investment for installation. Although some of the cost of sprinkler irrigation is associated with general maintenance, the majority of the cost is related to the purchase price of the water, which can be exorbitant, particularly in arid regions. Another problem associated with sprinkler irrigation, as well as with other watering methods, is that the fertilizers and nutrients used by the grass are leached away as the water percolates through the ground.
One method for reducing irrigation requirements and, hence the overall costs associated with maintaining sod, is with the use of hydrophilic polymers. Hydrophilic polymers are able to capture and retain up to several hundred times their weight in water. Accordingly, hydrophilic polymers can be used to generally increase the water holding capacity of the soil. More particularly, when water is supplied to grass sod, it is absorbed and stored by the hydrophilic polymers until the water is needed and used by the grass. When used in this manner, hydrophilic polymers can generally reduce irrigation requirements by about 30% to 60%. Agricultural and horticultural uses of hydrophilic polymers, such as polyacrylamide, are well known in the art.
There are different methods for applying hydrophilic polymers to grass sods. The polymers may, for example, be applied to the soil prior to growing the sod or, alternatively, the polymers can be applied to existing sod. It is difficult to apply hydrophilic polymers to existing sod, however, because the polymers must be inserted below the exposed grass layer and into or proximate the roots of the grass. It will be appreciated that this is not an easy task because the polymer cannot flow through the grass and into the soil while embodied in granular form. The polymer also cannot be sprayed and absorbed into the soil with an aqueous solution because the polymer cannot be diluted or otherwise suspended in water. In particular, once the polymer is introduced to water it will absorb the water, swell in size, and generally turn into a gel-like substance that cannot be absorbed through the sod.
Currently, there are three known prior art methods for placing hydrophilic polymers into the soils of mature sods. The first generally involves boring a hole into the sod with pressurized water and then using pressurized air to blow the polymer into the hole. The second method generally involves forming holes by removing small plugs out of the sod with small tubes, such as is done during aeration, and then dropping the polymer into the holes. These methods, however, are not very efficient. In particular, it has been found according to one study that they are only able to actually place about 20% to 30% of the polymer into the holes that are formed. The remainder of the polymer remains on the surface of the exposed grass where it provides no benefit. This is not only inefficient, but it can also create a hazardous condition. In particular, the polymer remaining on the top surface of the grass becomes very slippery when it is hydrated. Polymer left exposed on the grass surface is also accessible to be ingested by small children and animals. Yet another consequence of leaving the polymer on the surface of the grass is that it is relatively expensive, particularly when considering approximately 70% to 80% of the polymer product is essentially wasted since the water captured by the exposed polymer is inaccessible to the roots of the grass. For at least these reasons, the first two methods and apparatus for depositing hydrophilic polymers are undesirable because they are unable to effectively deposit the substantial entirety of the polymer into the sod and beneath the exposed grass surface where it is beneficial.
The third existing method for placing polymer into the soil of grass sod involves cutting and temporarily uprooting small sections of sod while the polymer is blown or otherwise applied to the soil under the sod. This method overcomes several of the aforementioned problems by ensuring the polymer is deposited below the exposed surface of the sod where it can provide utility. However, this method is also problematic because it can cause significant disruption to the root systems of the sod when the sod is temporarily uprooted. Uprooting sod is also problematic because it can temporarily or permanently disrupts the substantially smooth appearance surface of the exposed grass surface, thereby frustrating the aesthetics provided by the sod.
Yet another problem with each of the aforementioned methods for depositing hydrophilic polymers into the soils of existing sod is that they are slow which, it will be appreciated, increases the costs associated with applying the polymer. Existing devices, for example, are only presently able to deposit polymer into existing sod at rates of approximately 3,000 ft2/hr to 4,000 ft2/hr, taking approximately 11 to 14 hours to treat a single acre, during which time the device must be operated by a paid worker.
Accordingly, there is currently a need in the art for improved apparatus and methods for placing hydrophilic polymers into soils of existing grass sods.
The present invention generally relates to improved apparatus and methods for depositing hydrophilic polymers into existing sod in a controlled, efficient and relatively non-invasive manner.
In one preferred embodiment, the improved apparatus of the invention includes a frame, a cylindrical housing, spikes protruding radially away from the cylindrical housing, two rotating hubs, a tank, tubing connecting the fluid reservoir to the rotating hubs, tubing connecting the rotating hubs to the spikes, and a pump for pumping fluid from the tank to the rotating hubs where the fluid is forced into the spikes and ultimately into the earth.
According to one aspect of the invention, the frame is mounted to a driving mechanism that pushes and/or pulls the frame and generally causes the cylindrical housing and rotating hubs to rotate about a central axle of the rotating hubs. Fluid from the tank is pumped through the central axle and iteratively distributed through the rotating hubs to internal tubing that carries the fluid to the plurality of spikes that are attached to the cylindrical housing.
As the cylindrical housing rotates, the spikes are iteratively forced into the soil. Each spike is configured with a tapered end and an outlet hole located at the backside of the tapered end. During use, the rotating hubs channel the fluid into the spikes, but only while the spikes are inserted within the existing sod, thereby preventing the fluid from being discarded and ultimately wasted on the exposed surface of the sod. A computerized speed sensor and pressure regulator can be used to ensure the fluid is deposited at the appropriate time and with an appropriate amount of pressure.
According to one aspect of the invention, the apparatus of the invention further includes a secondary roller that is attached to the frame and which rolls on the surface of the ground behind the cylindrical housing. This secondary roller applies an appropriate force to the surface of the ground to substantially flatten out any sod that is displaced by the spikes as they are forcibly rotated through the sod.
It will be appreciated that this invention generally enables controlled and efficient deposition of hydrophilic polymer into existing sod and at desired depths, which not only reduces the costs associated with placing the polymer but also improves the general utility of the polymer once it is placed. The methods and apparatus of the invention provide an improvement over prior art devices for at least reducing the disruption that is caused to the sod, while at the same time enabling controlled and efficient distribution of the hydrophilic polymer into the sod.
These and other benefits, features, and advantages of the present invention will become more fully apparent from the following description, or may be learned by the practice of the invention as set forth hereinafter.